Abstract: Determining an optimal path through a storage area network from a specific initiator to a specific target includes determining a plurality of possible paths through the storage area network between the specific initiator and the specific target, examining a plurality of previously-determined latency values for each of the paths, the previously-determined latency values being set according to empirical observation of propagation through each of the paths, and choosing a specific one of the paths having a lowest latency value. The previously-determined latency values may be determined by sending a command from the specific initiator to the specific target. The command may avoid queuing any I/O operations at the specific target. The command may be a status request command or a vendor specific command. The source may be a host system and the target may be a storage system. The previously-determined latency may be measured using a PowerPath Management Appliance.

Abstract: A host device is configured to communicate over a network with a storage system comprising a plurality of storage devices. The host device comprises a multi-path input-output (MPIO) driver configured to control delivery of input-output (IO) operations from the host device to the storage system over selected ones of a plurality of paths through the network, where the paths are associated with respective initiator-target pairs, and each of a plurality of targets of the initiator-target pairs comprises a corresponding port of the storage system. The MPIO driver is further configured to obtain from the storage system information characterizing failure status of at least a subset of the targets, and to update availability status of the paths based at least in part on the obtained information.